Subject: Re: [linux-audio-user] rtc patching
From: Jörn Nettingsmeier (nettings_AT_folkwang-hochschule.de)
Date: Fri Sep 14 2001 - 11:28:11 EEST
Josh Green wrote:
>
> The RTC helps only for programs that use it. It just
> provides a nice time event source for doing time critical
> things like MIDI sequencing, etc. It doesn't really relate
> to latency. If your latency is still bad after applying
> Andrew Morton's patch then make sure that you actually
> enabled it "Low Latency Scheduling" and if you checked the
> "Control low latency with sysctl" that you do a "echo '1'
> >/proc/sys/kernel/lowlatency" to enable it on boot or
> whenever you feel like it :) Hard disk access can be a major
> source of latency spikes, make sure you are running it in
> DMA mode. Dave Philips wrote a good article on Linux Low
> Latency, you can find it here:
> http://linux.oreillynet.com/pub/a/linux/2000/11/17/low_latency.html
> Hope you can figure out whats causing your latency problems.
> Benno's latencytest program is one way to test your system
> (Dave's article talks about this). Lates..
> Josh Green
just for clarification, i think there are two versions of "rtc".
one is the kernel option "enhanced real-time clock support" (which
is in the standard kernel and thus needs no patch).
but some folks on alsa-dev wondered why the alsa-driver would not
find it and print "no rtc kernel patch" during ./configure.
IIRC, it turned out that there is another (experimental)
real-time-clock patch included in alsa-cvs, and the configure option
in the alsa driver is meant for that one. i don't know what it does,
and i have never used it.
-- Jörn Nettingsmeier home://Kurfürstenstr.49.45138.Essen.Germany phone://+49.201.491621 http://spunk.dnsalias.org http://www.linuxdj.com/audio/lad/
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